The present invention relates to a cooler for automotive use, more particularly, to an automotive cooler using a combination of a heat pipe and solar cells.
The operating principles of a conventional cooler for automotive use are as follows: A coolant-filled compressor is operated by the driving force of the rotary shaft of an engine transmitted to the compressor by a suitable means such as a belt. The compressed coolant is supplied to an evaporator section which is cooled by the latent heat of evaporation of the coolant. The air in the passenger compartment is circulated through the evaporator section with a fan so as to force cold air back into the compartment.
By directly using the power of the engine, the conventional cooler system has a high cooling capability but, on the other hand, it does not function at all unless the engine is in operation. The passenger compartment of a parked car on a midsummer day may become so hot as to make the occupants feel very uncomfortable.
One approach that has been proposed for avoiding this problem is to use a timer that automatically starts the engine just before the driver sits behind the wheel, thereby operating the cooler. However, this method has not been brought into commercial use for safety reasons.
A proposal has been made for making use of the strong sunshine on a midsummer day by generating power with a solar cell. However, commercial solar cells with an efficiency of 10% yield a power output of only 100 W/m.sup.2, even on a very hot day. This means that even if the roof of a passenger car were entirely covered with solar cells, the electricity output obtained is no more than 100 W, which is far short of the power requirement for operating a compressor. The car's battery could be used as an auxiliary power source, but this method is not advisable since the battery will be readily discharged, possibly rendering subsequent starting impossible. Another approach is to reduce the temperature elevation in the passenger compartment by a fan operated by solar cells. This method, however, has not proved very effective.